Fix timeouts in sys_pselect7

Fix timeouts in sys_pselect7

[Bernd Schmidt]

[-- Attachment #1: Type: text/plain, Size: 947 bytes --]

Since we (Analog Devices) updated our Blackfin kernel to 2.6.28, we've
seen occasional 5-second hangs from telnet.  telnetd calls select with a
NULL timeout, but with the new kernel, the system call occasionally
returns 0, which causes telnet to call sleep (5).  This did not happen
with earlier kernels.

The code in sys_pselect7 looks a bit strange, in particular the variable
"to" is initialized to NULL, then changed if a non-null timeout was
passed in, but not used further.  The patch below passes it to
core_sys_select instead of &end_time, and this appears to fix the
problem.  Does this look like the correct approach?

Signed-off-by: Bernd Schmidt <bernd.schmidt@analog.com>
-- 
This footer brought to you by insane German lawmakers.
Analog Devices GmbH      Wilhelm-Wagenfeld-Str. 6      80807 Muenchen
Sitz der Gesellschaft Muenchen, Registergericht Muenchen HRB 40368
Geschaeftsfuehrer Thomas Wessel, William A. Martin, Margaret Seif

[-- Attachment #2: select.diff --]
[-- Type: text/plain, Size: 530 bytes --]

 fs/select.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/select.c b/fs/select.c
index 08b91be..b0cf1f0 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -610,7 +610,7 @@ asmlinkage long sys_pselect7(int n, fd_set __user *inp, fd_set __user *outp,
 		sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
 	}
 
-	ret = core_sys_select(n, inp, outp, exp, &end_time);
+	ret = core_sys_select(n, inp, outp, exp, to);
 	ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
 
 	if (ret == -ERESTARTNOHAND) {

Re: Fix timeouts in sys_pselect7

[Ulrich Drepper]

On Tue, Jan 13, 2009 at 9:29 AM, Bernd Schmidt <bernds_cb1@t-online.de> wrote:
> The patch below passes it to
> core_sys_select instead of &end_time, and this appears to fix the
> problem.  Does this look like the correct approach?

Yes, that change is correct.


> Signed-off-by: Bernd Schmidt <bernd.schmidt@analog.com>

Reviewed-by: Ulrich Drepper <drepper@redhat.com>

Re: Fix timeouts in sys_pselect7

[Robin Getz]

On Tue 13 Jan 2009 14:38, Ulrich Drepper pondered:
> On Tue, Jan 13, 2009 at 9:29 AM, Bernd Schmidt <bernds_cb1@t-online.de> wrote:
> > The patch below passes it to
> > core_sys_select instead of &end_time, and this appears to fix the
> > problem.  Does this look like the correct approach?
> 
> Yes, that change is correct.
> 
> > Signed-off-by: Bernd Schmidt <bernd.schmidt@analog.com>
> 
> Reviewed-by: Ulrich Drepper <drepper@redhat.com>

Tested-by: Robin Getz <rgetz@blackfin.uclinux.org>

I'm assuming this should go into stable then?

Fix timeouts in sys_pselect7

[Bernd Schmidt]

[-- Attachment #1: Type: text/plain, Size: 964 bytes --]

Since we (Analog Devices) updated our Blackfin kernel to 2.6.28, we've
seen occasional 5-second hangs from telnet.  telnetd calls select with a
NULL timeout, but with the new kernel, the system call occasionally
returns 0, which causes telnet to call sleep (5).  This did not happen
with earlier kernels.

The code in sys_pselect7 looks a bit strange, in particular the variable
"to" is initialized to NULL, then changed if a non-null timeout was
passed in, but not used further.  It needs to be passed to
core_sys_select instead of &end_time.

Signed-off-by: Bernd Schmidt <bernd.schmidt@analog.com>
Reviewed-by: Ulrich Drepper <drepper@redhat.com>
Tested-by: Robin Getz <rgetz@blackfin.uclinux.org>
-- 
This footer brought to you by insane German lawmakers.
Analog Devices GmbH      Wilhelm-Wagenfeld-Str. 6      80807 Muenchen
Sitz der Gesellschaft Muenchen, Registergericht Muenchen HRB 40368
Geschaeftsfuehrer Thomas Wessel, William A. Martin, Margaret Seif


[-- Attachment #2: select.diff --]
[-- Type: text/plain, Size: 531 bytes --]

 fs/select.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/select.c b/fs/select.c
index 08b91be..b0cf1f0 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -610,7 +610,7 @@ asmlinkage long sys_pselect7(int n, fd_set __user *inp, fd_set __user *outp,
 		sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
 	}
 
-	ret = core_sys_select(n, inp, outp, exp, &end_time);
+	ret = core_sys_select(n, inp, outp, exp, to);
 	ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
 
 	if (ret == -ERESTARTNOHAND) {